What was the Welsh not and when did they stop using it?
Ateb
The 'Welsh not' was a piece of wood (with either W.N. or Welsh Not carved into it) that was hung around the neck of a child that spoke Welsh during school hours. If another child was heard speaking Welsh, the piece of wood would be passed to him to to be put around his neck. At the end of the week, the child with the W.N. around his neck would be punished by lashing. The practice was gradually abolished from the late 1880s onwards.